Public Release:  Atmospheric pressure plasma jet from a grounded electrode

American Institute of Physics

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College Park, MD (August 24, 2010) -- Because they are portable and easy to operate at ambient temperatures, cold atmospheric pressure plasma jets (APPJs) should find innovative applications in biomedicine, materials science and fabrication industries. Research reported in the Journal of Applied Physics investigates an APPJ that extends from the ground electrode of a circuit.

The researchers studied the mechanism of the jet, which differs from conventional APPJ applications that form at the active electrode.

"The ground electrode jets originate from a charge overflow and are powered by the dielectric barrier discharge between the electrodes," say authors Nan Jiang and Zexian Cao of the Beijing National Laboratory for Condensed Matters in China. "They are therefore isolated from electrical breakdown when the jet approaches an object."

This separation between the jet and active electrode, along with the ability to form a jet at lower voltages than conventional APPJs increases operator safety and opens up biomedical applications that would be dangerous otherwise.

By using narrow, transparent ground electrodes, the researchers found that the overflow jet begins to develop at the inner edge of the ground electrode, and propagates forward in the dielectric via surface microdischarge which, to the surprise of the authors, causes backstreaming of charges. The output characteristics of the jet can be tuned by adjusting the conditions of dielectric barrier discharge between the electrodes and by varying the width of the ground electrode.

"This allows a flexible, miniaturized design since it is the ground electrode that sits at the front part of the device," says Cao. Further research will strive for a detailed understanding of the processes involved in the generation of such plasma jets, for example, the interplay of charged jet with the carrier gas flow, shown in the accompanying illustration.

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The article, "Atmospheric Pressure Plasma Jets beyond Ground Electrode as Charge Overflow in a Dielectric Barrier Discharge Setup" by Nan Jiang, Ailing Ji and Zexian Cao will appear in the Journal of Applied Physics. See: http://jap.aip.org/resource/1/japiau/v108/i3/p033302_s1

Journalists may request a free PDF of this article by contacting jbardi@aip.org

NOTE: An image is available for journalists. Please contact jbardi@aip.org

Image Caption: Photographs of atmospheric pressure plasma jet and Schlieren photograph of helium gas flow showing obvious interplay of the jet with the carrying gas flow. Numbers at left specify the gas flow rate in liter/hour. Applied voltage: 8 kV

ABOUT Journal of Applied Physics

Journal of Applied Physics is the American Institute of Physics' (AIP) archival journal for significant new results in applied physics; content is published online daily, collected into two online and printed issues per month (24 issues per year). The journal publishes articles that emphasize understanding of the physics underlying modern technology, but distinguished from technology on the one side and pure physics on the other. See: http://jap.aip.org/

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The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world's largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.

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